1. Field of the Invention
The present invention relates to a spacer assembly used in a flat panel display apparatus, a method of manufacturing a spacer assembly, a flat panel display apparatus with a spacer assembly, a method of manufacturing a flat panel display apparatus, and a mold used in the manufacture of a spacer assembly.
2. Description of the Related Art
A flat panel display apparatus represented by a liquid crystal display apparatus has been widely used in various fields as a display apparatus that replaces a cathode ray tube (CRT). A liquid display apparatus, however, has several problems to be solved; for example, it does not emit light by itself and its display performance has view angle dependency.
In this situation, a self emission type flat panel display apparatus such as a field emission display (FED) or plasma display (PDP) is under development. For example, a surface conduction type electron-emitting display (SED) as one type of the FED has been intensively studied and developed because it can ensure good display characteristics compatible with those of a CRT.
This SED has a face plate and rear plate opposing each other at a predetermined gap. These plates are bonded to each other at their peripheries through a rectangular frame-like side wall, thus constituting a vacuum envelope. Three color phosphor layers are formed on the inner surface of the face plate, and a number of emitters corresponding to respective pixels are arranged on the inner surface of the rear plate to serve as electron-emitting sources for exciting phosphors. Each emitter is comprised of an electron-emitting portion, a pair of electrodes for applying a voltage to the electron-emitting portion, and the like.
A plate-like grid is disposed between the two plates. The grid has a number of apertures located to be aligned with the emitters, and a number of columnar spacers are arranged on the grid for maintaining the gap between the plates. An electron beam emitted from each emitter passes through the corresponding aperture of the grid and is converged on a desired phosphor layer.
As an FED having a spacer assembly comprised of a grid and spacers as described above, one disclosed in U.S. Pat. No. 5,846,205 is known. According to this FED, a plate-like grid has a number of spacer holes. A columnar spacer with a diameter slightly smaller than that of the spacer hole is inserted in each spacer hole, and is adhered and fixed to the grid with an adhesive frit glass, solder, or the like. Each spacer projects from the two surfaces of the grid, and its two ends abut against the inner surfaces of the face plate and rear plate, respectively.
As described above, when a spacer assembly is to be manufactured by inserting columnar spacers in a number of spacer holes formed in a grid and fixing them by using an adhesive or the like, the manufacture becomes very cumbersome, and it is difficult to improve the manufacturing efficiency. More specifically, each spacer is as very small as several 100 xcexcm in diameter and several mm in height, and the spacer hole corresponding to it is also very small. To correctly insert such a very small spacer in the spacer hole of the grid and adhere it to the grid by using an adhesive or the like, high assembly precision is required. This makes the operation very difficult and leads to an increase in manufacturing cost and a decrease in manufacturing efficiency.
The present invention has been made in view of the above situation, and has as its object to provide a spacer assembly for a flat panel display apparatus which can be manufactured easily, a flat panel display apparatus having a spacer assembly, a method of manufacturing a spacer assembly, a mold used in the manufacture of a spacer assembly, and a flat panel display apparatus which can prevent a decrease in display quality from being caused by charging of the spacer while a sufficiently high strength is ensured.
In order to achieve the above object, according to an aspect of the present invention, a method of manufacturing a spacer assembly having a substrate and a plurality of columnar spacers formed on the substrate and used for a flat panel display apparatus, comprises:
preparing a substrate and a mold with a number of through holes,
arranging the mold on a surface of the substrate to be in tight contact therewith and filling the through holes of the mold with a spacer forming material,
curing the spacer forming material by irradiation with radiation, thereby increasing adhesion of the spacer forming material with respect to the surface of the substrate to be higher than that of the spacer forming material with respect to the mold,
calcining the spacer forming material with the mold being in tight contact with the substrate, thereby forming spacers on the substrate, and
after cooling, releasing the mold from the substrate.
A method of manufacturing a spacer assembly according to another aspect of the present invention comprises
preparing a substrate having opposing first and second surfaces and a plurality of through holes, and first and second molds each having a plurality of through holes,
arranging the first and second molds on the first and second surfaces of the substrate to be in tight contact therewith such that the holes of the substrate and the through holes of the first and second molds are aligned with each other, and thereafter filling the through holes of the first and second mold with a spacer forming material,
curing the spacer forming material by irradiation with radiation, thereby increasing adhesion of the spacer forming material with respect to the substrate to be higher than that of the spacer forming material with respect to the first and second molds,
calcining the spacer forming material with the first and second molds being in tight contact with the substrate, thereby forming spacers on the first and second surfaces of the substrate, and
after cooling, releasing the first and second molds from the substrate.
A method of manufacturing a spacer assembly according to another aspect of the present invention comprises:
preparing a substrate having opposing first and second surfaces, and first and second molds each having a plurality of through holes,
arranging the first mold on the first surface of the substrate to be in tight contact therewith, and thereafter filling the through holes of the first mold with a spacer forming material,
curing the spacer forming material by irradiation with radiation, thereby increasing adhesion of the spacer forming material with respect to the first surface of the substrate to be higher than that of the spacer forming material with respect to the first mold,
arranging the second mold on the second surface of the substrate to be in tight contact therewith, and filling the through holes of the second mold with a spacer forming material,
curing the spacer forming material by irradiation with radiation, thereby increasing adhesion of the spacer forming material with respect to the second surface of the substrate to be higher than that of the spacer forming material with respect to the second mold,
after irradiation with the radiation, calcining the spacer forming material with the first and second molds being in tight contact with the substrate, thereby forming spacers on the first and second surfaces of the substrate, and
after cooling, releasing the first and second molds from the substrate.
According to the manufacturing method described above, a glass paste containing at least an ultraviolet-curing binder and a glass filler is used as the spacer forming material, and in this case, the spacer forming material is cured by irradiation with ultraviolet rays as radiation.
As the substrate, a metal plate having a surface with an oxide film formed on it, a grid formed of a metal plate having a number of apertures and a surface with an oxide film formed on it, or a glass substrate can be used. As the mold, one subjected to surface treatment having releasability with respect to the spacer forming material and oxidation resistance is preferably used.
According to the method of manufacturing the spacer assembly with the above arrangement, a spacer forming material is calcined as it is arranged on a substrate or grid by using a mold, so a plurality of spacers can be built at predetermined positions on the substrate or grid at once. As a result, a spacer assembly with a plurality of small spacers can be manufactured easily, and the manufacturing cost can be reduced and the manufacturing efficiency can be improved.
The spacer forming material is calcined as it fills the through holes of the mold. Thus, during calcination, the spacer forming material will not be squeezed to spread, so spacers each with a sufficiently large height and high aspect ratio can be formed easily.
Furthermore, as the spacer forming material, a glass paste containing an ultraviolet-curing binder and a glass filler is used. Before calcination, the spacer forming material is cured by irradiation with ultraviolet rays, and a grid covered with an oxide film and a mold covered with an oxidation-resistant surface layer are used. Thus, adhesion of the spacer with respect to the substrate or grid can be increased to be higher than that with respect to the mold. As a result, in the following calcining and releasing steps, the formed spacers are prevented from attaching to the mold, so spacers integral with the substrate or grid can be formed reliably.
According to an aspect of the present invention, there is provided a method of manufacturing a flat panel display apparatus including a first substrate having an inner surface on which phosphor layers are formed, a second substrate arranged to oppose the first substrate at a predetermined gap and provided with phosphor exciting sources configured to excite the phosphor layers, a frame-like side wall that joins peripheries of the first and second substrates, a plate-like grid arranged between the first and second substrates to oppose the substrates and having a number of apertures located to correspond to the phosphor exciting sources, a number of columnar first spacers arranged between the first substrate and the grid, and a number of columnar second spacers arranged between the second substrate and the grid, the method comprising:
preparing a grid and a mold with a number of through holes, arranging the mold on a surface of the grid to be in tight contact therewith and filling the through holes of the mold with a spacer forming material, curing the spacer forming material by irradiation with radiation, thereby increasing adhesion of the spacer forming material with respect to the surface of the grid to be higher than that of the spacer forming material with respect to the mold, calcining the spacer forming material with the mold being in tight contact with the substrate, thereby forming the large number of first spacers on the grid, and after cooling, releasing the mold from the grid.
A flat panel display apparatus according to another aspect of the present invention comprises a first substrate having an inner surface with a phosphor layer formed thereon, a second substrate arranged to oppose the first substrate at a predetermined gap and provided with phosphor exciting sources configured to excite the phosphor layer, a frame-like side wall that joins peripheries of the first and second substrates, a plate-like grid arranged between the first and second substrates to oppose the substrates and having a number of apertures located to correspond to the phosphor exciting sources, a plurality of columnar first spacers arranged between the grid and the first substrate, and a plurality of columnar second spacers arranged between the grid and the second substrate, and wherein a height of each of the first spacers is larger than that of each of the second spacers.
In the flat panel display apparatus, the grid has a first surface opposing the first substrate and a second surface opposing the second substrate, and the first spacers vertically stand on the first surface of the grid to be integral therewith and the second spacers vertically stand on the second surface of the grid to be integral therewith.
A spacer assembly according to another aspect of the present invention comprises a substrate and a plurality of columnar spacers vertically standing on the substrate to be integral therewith. Each of the spacers integrally has a plurality of steps stacked from the substrate toward an extending end and with diameters that decrease gradually, and each of the steps is formed in a tapered shape to be thinner from the substrate toward the extending end.
A spacer assembly according to another aspect of the present invention comprises a plate-like grid having first and second opposing surfaces and a plurality of apertures, a plurality of columnar first spacers vertically standing on the first surface of the grid to be integral therewith, and a plurality of columnar second spacers vertically standing on the second surface of the grid to be integral therewith. Each of the first and second spacers integrally has a plurality of steps stacked from the grid toward an extending end and with diameters that decrease gradually, and each of the steps is formed in a tapered shape to be thinner toward an extending end.
A flat panel display apparatus according to another aspect of the present invention comprises a first substrate having an inner surface with a phosphor layer formed thereon, a second substrate arranged to oppose the first substrate at a predetermined gap and provided with phosphor exciting sources configured to excite the phosphor layer, a frame-like side wall that joins peripheries of the first and second substrates, and a spacer assembly formed between the first and second substrates. The spacer assembly has a plate-like grid having a number of apertures opposing the phosphor exciting sources, and a plurality of columnar spacers standing vertically on the grid to be integral therewith. Each spacer integrally has a plurality of steps stacked from the grid toward an extending end and with diameters that decrease gradually, and each step is formed in a tapered shape to be thinner toward the extending end.
According to the spacer assembly and flat panel display apparatus with the above arrangement, each spacer integrally has a plurality of steps stacked toward an extending end and with diameters that decrease gradually, and each step is formed in a tapered shape to be thinner toward the extending end, thus forming a stepped taper as a whole, i.e., a substantially stepped truncated conical shape. Therefore, a plurality of spacers can be integrally built on the substrate or grid with a mold or the like, and a spacer assembly and a flat panel display apparatus that can be manufactured easily can be obtained.
A method of manufacturing a spacer assembly according to another aspect of the present invention comprises preparing a substrate and a plate-like mold having a plurality of stepped tapered through holes each with a diameter that decreases gradually from one end toward the other end thereof, arranging the mold on a surface of the substrate to be in tight contact therewith such that large-diameter sides of the through holes are located on a substrate side and filling the through holes of the mold with a spacer forming material, curing the spacer forming material by irradiation with radiation, thereby increasing adhesion of the spacer forming material with respect to the surface of the substrate to be higher than that of the spacer forming material with respect to the mold, calcining the spacer forming material with the mold being in tight contact with the substrate, thereby integrally forming spacers on the substrate, and after cooling, releasing the mold from the substrate.
Another method of manufacturing a spacer assembly according to another aspect of the present invention comprises preparing a plate-like grid with first and second surfaces and a plurality of spacer holes located between the apertures, preparing plate-like first and second molds having a plurality of stepped tapered through holes each with a diameter that decreases gradually from one end toward the other end thereof, bringing the first and second molds into tight contact with the first and second surfaces of the grid such that large-diameter sides of the through holes are located on a grid side and arranging the first and second molds such that the spacer holes of the grid and the through holes of the first and second molds are aligned, and filling the through holes of the first and second molds with a spacer forming material, curing the spacer forming material by irradiation with radiation, thereby increasing adhesion of the spacer forming material with respect to the grid to be higher than that of the spacer forming material with respect to the first and second molds, calcining the spacer forming material with the first and second molds being in tight contact with the grid, thereby forming spacers on the first and second surfaces of the grid, and after cooling, releasing the first and second molds from the grid.
Still another method of manufacturing a spacer assembly according to an aspect of the present invention comprises preparing a plate-like grid having first and second surfaces, preparing plate-like first and second molds having a number of stepped tapered through holes each with a diameter that decreases gradually from one end toward the other end thereof, arranging the first mold on the first surface of the grid to be in tight contact therewith such that large-diameter sides of the through holes are located on a grid side, and filling the through holes of the first mold with a spacer forming material, curing the spacer forming material by irradiation with radiation, thereby increasing adhesion of the spacer forming material with respect to the first surface of the grid to be higher than that of the spacer forming material with respect to the first mold, arranging the second mold on the second surface of the grid to be in tight contact therewith such that large-diameter sides of the through holes are located on a grid side, and filling the through holes of the second mold with a spacer forming material, curing the spacer forming material by irradiation with radiation, thereby increasing adhesion of the spacer forming material with respect to the second surface of the grid to be higher than that of the spacer forming material with respect to the second mold, after irradiation with the radiation, calcining the spacer forming material with the first and second molds being in tight contact with the grid, thereby forming spacers on the first and second surfaces of the grid, and after cooling, releasing the first and second molds from the substrate.
According to an aspect of the present invention, in the above manufacturing method, a glass paste containing an ultraviolet-curing binder and a glass filler is used as the spacer forming material. In this case, the spacer forming material is cured by irradiation with ultraviolet rays as the radiation. As the substrate, a metal plate with a surface formed with an oxide film, a grid formed of a metal plate having a number of apertures and a surface formed with an oxide film, or a glass substrate can be used.
According to the spacer assembly manufacturing method with the above arrangement, a spacer forming material is calcined as it is arranged on a substrate or grid by using a mold, so a plurality of spacers can be built at predetermined positions on the substrate or grid at once. As a result, a spacer assembly with a plurality of small spacers can be manufactured easily, and the manufacturing cost can be reduced and the manufacturing efficiency can be improved.
The spacer forming material is calcined as it fills the through holes of the mold. Thus, during calcination, the spacer forming material will not be squeezed to spread, so spacers each with a sufficiently large height and high aspect ratio can be formed easily.
Furthermore, as the spacer forming material, a glass paste containing at least an ultraviolet-curing binder and a glass filler is used. Before calcination, the spacer forming material is cured by irradiation with ultraviolet rays, and a grid covered with an oxide film and a mold covered with an oxidation-resistant surface layer are used. Thus, adhesion of the spacer with respect to the substrate or grid can be increased to be higher than that with respect to the mold. As a result, in the following calcining and releasing steps, the formed spacers are prevented from attaching to the mold, so spacers integral with the substrate or grid can be formed reliably.
A mold used in the manufacture of a spacer assembly according to an aspect of the present invention comprises a plurality of metal thin plates each having a plurality of tapered through holes, each of the through holes of each of the metal thin plates has a diameter different from those of through holes of other metal thin plates, and the plurality of metal thin plates are stacked such that their through holes are aligned with each other and such that the through holes sequentially line up in descending order of diameter.
With the above arrangement, the mold is formed by stacking a plurality of metal thin plate each with through holes, and each through hole of the mold is defined by overlaying a plurality of through holes. In the case of a metal thin plate, small through holes can be formed comparatively easily by etching, laser irradiation, or the like. Therefore, when these plurality of metal thin plates are stacked, a mold having through holes with desired heights can be obtained easily.
In the above mold, the through holes formed in each metal thin plate are tapered, and their diameters differ from one metal thin plate to another. When these plurality of metal thin plates are to be stacked, even if some misalignment occurs, the through holes of the metal thin plates are caused to reliably communicate with each other, and a mold with desired through holes can be obtained.
Furthermore, according to an aspect of the present invention, the mold is covered with a surface layer having releasability with respect to the spacer forming material. Hence, the spacer forming material does not easily attach to the inner portions of the through holes of the mold, and the mold can be repeatedly used for the manufacture of a spacer assembly.
A flat panel display apparatus according to another aspect of the present invention comprises a face plate and a rear plate arranged to oppose each other at a predetermined gap, and a spacer assembly disposed between the face plate and the rear plate, wherein the spacer assembly has an electrode plate having opposing first and second surfaces and a plurality of spacer holes and arranged between the face plate and the rear plate to oppose the face plate and the rear plate, a plurality of first spacers formed on the first surface of the electrode plate, a plurality of second spacers formed on the second surface of the electrode plate, and a connecting portion connecting one of the second spacers to a plurality of first spacers to each other through corresponding spacer holes formed in the electrode plate.
Another flat panel display apparatus according to an aspect of the present invention comprises a face plate with an inner surface with a phosphor layer formed thereon, a rear plate arranged to oppose the face plate at a predetermined gap and provided with a plurality of electron-emitting portions for exciting the phosphor layer, a frame-like side wall that joins peripheries of the face plate and the rear plate, and a spacer assembly formed between the face plate and the rear plate.
The spacer assembly has an electrode plate having opposing first and second surfaces and a plurality of spacer holes and arranged between the face plate and the rear plate to oppose the face plate and the rear plate, a plurality of first spacers formed on the first surface of the electrode plate and in contact with the face plate, and a plurality of second spacers formed on the second surface of the electrode plate and in contact with the rear plate. One of the second spacers is connected to a plurality of first spacers to each other with a connecting portion through corresponding spacer holes formed in the electrode plate.
According to the flat panel display apparatus with the above arrangement, the spacer assembly has a plurality of first spacers formed on a first surface of the electrode plate and a plurality of second spacers formed on a second surface of the electrode plate. One second spacer is arranged to be connected to a plurality of first spacers to each other through a connecting portion. Therefore, a sufficiently high structural strength can be ensured for the spacer assembly, and a sufficiently large aspect ratio can be ensured for the first spacers, so the adverse influence of charging of the first spacers can be reduced.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.